According to reliable sources Cesc Fábregas was tempted to leave Arsenal a year ago but was persuaded to give it another season. He gambled those 12 months out of loyalty to Arsène Wenger and perhaps because he really thought he could hear the train of the team's greatness rattling closer in the dark.

Wenger always promised it would get here. He still will, even if the side's best player rejoins his spiritual home. The Arsenal manager is a determinist who asks players and supporters to see through his eyes. The club's fans have stayed true to the vision of a self-perpetuating empire of home-reared talent (with some grumbling) and the players have mostly stuck by the creed. But it was always stretching hope to expect Fábregas to keep saying no to the club where he grew up and who inflicted the most brutal humiliation on the Gunners with their 4-1 Champions League win at the Camp Nou.

So if Arsenal acquiesce and let Fábregas return to Catalonia they will endure a mighty double blow. The first is that he sets the rhythm and tone of the team's play. He is the fetcher and distributor of endless midfield passes and is the one who can send a ball "with information on it" (as one Arsenal legend says) to turn a phase of play from meditation to attack. There are perhaps five central midfielders in world football who can open up a field so artfully and two of them are already at Barcelona: Xavi Hernández and Andrés Iniesta.

Second, the young captain's attempted defection says patience has expired and that players will now make their own minds up on whether a trophy-winning side is forming under the greenhouse lights of London Colney.

Here it ought to be emphasised that Fábregas's familial, emotional and stylistic ties with Barcelona are unusually strong. Cristiano Ronaldo insisted on leaving Manchester United to make a leap into the unknown.

Fábregas wants to go home, to a club that raised the Liga title last weekend while hailing the majesty of Lionel Messi, scorer of 47 goals. His homesickness cannot be read solely as a repudiation of Wenger's promises about this Arsenal team maturing into world-beaters. Yet his move would be a darkly cinematic moment in which the apprentice turned his back on the old master in search of something more tangible to believe in.

In his biography of Messi, Luca Caioli points out that Barcelona moved so quickly to sign "The Flea" partly because they were so traumatised about losing Fábregas to Arsenal in 2003, when he was 16. A talent drain on this scale strikes at the heart of a big club, and it may now be Arsenal's turn to experience the deflation felt by Manchester United when Ronaldo successfully asserted free will over contractual obligations and left for Madrid.

Fábregas has been used as an unofficial tutor to the likes of Alex Song, Abou Diaby, Aaron Ramsey and Denílson: teaching them the art of constructive passing and carrying them, often, through hard matches with his leadership and his goals. Remove those qualities from a sometimes lightweight Arsenal middle four and Wenger either needs to find some warriors in the Patrick Vieira/Emmanuel Petit mould or somehow cause his boys to become men overnight.

The strain on Fábregas was apparent long before he cracked his right fibula in the home leg against Barcelona. In an interview shortly before, he said: "I've given my all for Arsenal, I've played when I've felt ill, and through injury. I even played in the Champions League a few hours after my grandfather died."

In his programme notes he warned: "As a team we need to be stronger. We can't hide behind people saying we are too young, or have injuries. We just have to compete."

Instead, Arsenal, who have not lifted a trophy for five years and last won the league in 2004, finished 11 points behind Chelsea and were wiped out in Europe by the team Fábregas now wants to join. Watching that second leg from the Camp Nou stands, the former youth team-mate of Messi and Gerard Piqué must have been struck by the thought that he had the choice of playing for either team: the one with Messi in it, or the side who have banked everything on a one-plan style that yielded home and away defeats to Chelsea and Manchester United in the Premier League.

Wenger's pursuit of Marouane Chamakh, the 26-year-old Bordeaux striker, comes just in time to give the high command a chance of persuading Fábregas that Arsenal's reliance on scouted youth has not become a self-defeating obsession. But there will be others in this Arsenal squad who would interpret the soul being ripped from the team as a reason to test the market. Andrey Arshavin, another Barcelona fan, is one. Anxiety could also spread to Robin van Persie.

Groping for reasons to be cheerful, an Arsenal fan might say this marks the end for Wenger's utopian phase. Reality will dictate that the Fábregas money would have to be reinvested: not on more promising 19-year-olds but ready-made gladiators who know how to win.